Comment 7 for bug 492773

I think I've tracked this down.

In src/extension/internal/cairo-render-context.cpp there's a call to the function feed_pathvector_to_cairo() with two parameters. This function is defined in src/display/inkscape-cairo.cpp, and calls cairo_close_path(). And the documentation for cairo_close_path() - http://cairographics.org/manual/cairo-paths.html#cairo-close-path - says "any call to cairo_close_path() will place an explicit MOVE_TO element into the path immediately after the CLOSE_PATH element".

So I think that Cairo needs to supply an alternative to cairo_close_path() that doesn't include the MOVE_TO, and Inkscape needs to use this alternative function when writing PostScript. (To complicate matters, there are rare cases for which the MOVE_TO is actually required.)